1) Field of the Invention
The present invention relates to an electrophotographic process suitable for use in recording apparatuses such as printers and copying machines and also to an electrophotographic apparatus thereof.
2) Description of the Related Art
According to conventional electrophotography, an electrostatic latent image is formed on a photosensitive member, namely, on an electrostatic latent-image bearing member, the electrostatic latent image is developed to form a toner image, and the toner image is then transferred onto a support sheet, namely, onto a support member. This process is widely used in copying machines, printers and the like as it can provide records of high picture quality.
In general, an electrophotographic apparatus permitting high-speed recording is large and expensive and consumes large amounts of power. Users are therefore required to employ an electrophotographic apparatus or a printing machine by selecting either one of these depending on the number of copies to be made from the same original. This selection is certainly cumbersome to them.
When prints as few as several sheets are desired, it is preferred to make them by simply using an electrophotographic apparatus. On the other hand, in cases where several hundred or more copies are required, printing by a printing machine such as a stencil printing apparatus, a screen printing apparatus or an offset printing apparatus is preferred. For prints or copies where the number required falls between the two quantities described above, neither the electrophotographic apparatus nor the printing machine can fully satisfy the user's needs due to printing cost, printing time or the like.
An apparatus has hence been provided, which is usually employed as an electrophotographic apparatus but, when a large number of copies is needed, a toner image is first fused on a photosensitive member to prepare a master, the photosensitive member is next electrically charged through the toner image on the master while making use of light-shielding effects of the toner image, the thus-charged photosensitive member is then subjected to whole-surface exposure to promptly form an electrostatic latent image without scanning the original, and copies are then obtained (See Schaffert U.S. Pat. No. 2,576,047 issued Nov. 20, 1951; The 4th Symposium on Non-impact Printing Technology, "Xerography technology", pp 113-116).
Conventional electrophotographic processes and apparatuses however involve the problems that a photosensitive member with a toner image fused thereon cannot be reused and must be thrown away after completion of printing.
To overcome these problems, an apparatus has been provided. In this apparatus, a supply roller with a photosensitive sheet of a length equivalent to about 100 frames or so wound thereon and a take-up roller for winding up the photosensitive sheet after use are disposed within a drum so that the photosensitive sheet can be automatically supplied onto the drum.
However, the above apparatus has a complex construction and, depending on the manner of use, the photosensitive sheet inside the drum may have to be replaced frequently, resulting in a higher printing cost. In addition, the toner on the photosensitive member is heated directly so that the photosensitive member deteriorates and the potential charged on the photosensitive member thus varies. Further, the photosensitive member is electrically charged through the toner image so that the potential charged on the photosensitive member locally varies depending on the presence or absence of the toner image, thus causing a deterioration in the quality of the resulting picture.